In recent years, solar cells which can convert solar light into electrical energy have been used as an alternative energy source for petroleum. Solar cells include a monocrystalline solar cell, a polycrystalline solar cell, an amorphous solar cell, or a combination of these solar cells.
In a solar cell, in order to extract the generated electric power to the outside, a collecting electrode such as a finger portion and a bus bar portion is provided on a front surface and a back surface of the solar cell. In recent years, in consideration of the high conductivity, ease of machining, and price of material, a collecting electrode formed by plating is often employed, as described in Patent Document 1. When the collecting electrode is formed by plating, in the related art, materials such as nickel (Ni), copper (Cu), chrome (Cr), zinc (Zn), tin (Sn), and silver (Ag) are used. In particular, in relation to the cost and resistivity, copper is preferably used.